This invention relates to apparatus for accurately cutting materials at selected angles and more particularly to apparatus which operates in conjunction with a chain saw for accurately cutting materials such as logs and large timbers at selected angles. Interest in some areas of America's heritage, and concern about the excessive energy required to heat homes and structures built according to present day techniques has resulted in a renewed interest in homes and buildings constructed from logs and huge timbers. One reason for this renewed interest is that the insulation value of, for example, a wall made of 8-inch logs is significantly greater than the insulation value of an insulated frame wall on a typical american home. Unfortunately, buildings of the type erected by the early pioneers which used logs and large timbers also are not acceptable because of the cracks and air gaps left between the ill-fitting logs. These primitive walls therefore do not provide the insulation values for which they are capable, since the wind allows cold air to blow into the structure between adjoining logs. It is clear, therefore, that to appreciate the great insulation values of large timbers and logs, it is necessary that the logs or timber fit together such that they are airtight. To this end, modern homes made out of logs are constructed of logs having uniform sizes and mating surfaces. These techniques have been highly successful as far as achieving high insulation values for the basic outside walls of the structure. Unfortunately, because of variations from structure to structure of such buildings, those logs or timbers making up the side walls at the top of the structure which come to a peak as the wall forms the gable typically cannot be cut accurately enough to attach the roof in an air tight manner. These upper side walls are normally put into place in the same manner as the logs making up the rest of the side wall and then an attempt is made to carefully cut through each log or timber at an angle necessary to obtain the gable or slope of the roof. This technique is dangerous, and typically results in an uneven cut or roof pitch, which requires extensive filling of the spaces and gaps left because of such irregular cuts. Other approaches have been to simply not use the large logs or timbers for those portions of the wall forming a roof gable and instead use walls made by standard framing techniques for their upper walls. However, this approach is not as esthetically pleasing nor is it as effective in its insulation qualities as would be a well fitted solid log wall. Therefore, it is an object of this invention to provide apparatus for accurately and precisely cutting logs and large timbers at angles necessary for forming a roof gable.
Because of the large size of the logs and timbers used in modern log house structures, the standard 7 or 8 inch blade "skill" or bench saw typically used at home construction sites is just not suitable for cutting such large timbers. Furthermore, during the construction of such log buildings it is often necessary to make cutouts through solid walls made of such logs or timbers stacked on top of each other. Therefore, chain saws have become a functional and important tool at such construction sites. The chain saw is suitable for such uses because of its portability, its ease of handling and its ability to cut through large diameter timbers by means of a small machine. In the past, chain saws have been used as the primary means for cutting the topmost portion of a log wall at an angle necessary to form a roof gable. However, as was mentioned heretofore, efforts to accurately cut through a solid log wall at the proper angle with a chain saw to form an airtight fit with the roof has been unacceptable and dangerous. In general, chain saws have been around for many years in the logging industry and have been found to be a very versatile tool. Because of this versatility and their light weight, a number of improvements and adaptors which work with chain saws have been developed over the years. As an example, U.S. Pat. No. 1,861,162 issued to H. Quist on May 31, 1932, discloses apparatus for use with a chain saw to aid in cutting piles or other vertical timbers in which the weight of the chain saw must be supported to insure that the cut is made at the desired predetermined angle. According to this patent, this is accomplished by the use of guides rigidly attached to the chain saw which guides engaged battens secured to the pile to be cut. This technique is of course not suitable for cutting walls for structure at an angle because of the danger involved, and because of the need for carefully securing the battens to each of the logs being cut.
U.S. Pat. No. 2,463,860 issued to R. E. Foster on Mar. 8, 1949, discloses apparatus for supporting a large two-main chain saw such that huge timbers or logs may be cut by one person. This device includes a pointed drive member which is driven into the wood or timber at a location close to the position that the desired cut is to be made. Attached to this pointed drive member is an adjustable support arm which is used to engage a hole in the bar of the chain saw. The bar of the chain saw is then pivoted around the support arm to achieve the desired cut.
Another U.S. Pat. No. 2,698,034 issued to E. A. Jakku on Dec. 28, 1954, discloses still another apparatus which is attached to a chain saw. This patent discloses the use of several guards attached at selected location on the bar of the chain saw such that they extend perpendicular to and beyond the cutting portion of the cutting chain. These guards thereby provide a support for twigs and small limbs to bear against during the cutting operations such that the twigs or limbs will be held in place as they are being cut and not be swept into the face of the operator of the chain saw or out of reach of the cutting chain. It is obvious of course that this patent in no way discloses much less teaches apparatus for accurately cutting large timbers or logs with a chain saw.
U.S. Pat. No. 3,225,799 issued to E. A. Hayden et al. on Dec. 28, 1965 discloses chain saw apparatus for ripping logs which can be used at the location at which the felling operation takes place. According to this patent, a large log or timber can be cut lengthwise at the location that the tree is felled. It will be appreciated that although this device does allow logs to be cut by a chain saw into substantially regular size timbers, it in no way teaches a technique for precisely cutting logs and timbers at an angle suitable for use in forming the gable of a log structure.
U.S. Pat. No. 3,845,556 issued to T. H. Edmunson on Nov. 5, 1974, does disclose apparatus for use with a chain saw in cutting timbers at an angle. This device uses a cutting guide such as is used on a "skill" saw or bench saw for cutting timbers at an angle. The guide may also be used in combination with a ripping fence or track for cutting the timbers at certain angles such as would be necessary for the roof gable of a building. However, this apparatus must be securely mounted by large lag bolts to the timber being cut prior to the cut taking place. The use of such lag bolts may, of course, mar the lumber such that it is unsuitable for its intended use. Furthermore, this technique is extremely time consuming, is substantially only suitable for timbers having a square cross section and is not suitable for substantially cylindrically shaped logs. Thus, from the discussions of the above patents it is seen that although several types of apparatus have been developed for use with chain saws, none of these apparatus even suggest much less teach the apparatus of the present invention.
In addition to the apparatus described above, with respect to chain saws, the typical mitre box used in woodworking should be considered during a study of the background of this invention. It will be appreciated, that although the mitre box used in the standard woodworking shop and the device of this invention have similarities, the concept of using a large chain saw rather than a fine tooth hand saw is quite remote. In addition, mitre boxes are typically used for cutting small to medium size work pieces and have not found extensive use in cutting large timbers and especially cutting large cross-sectional logs.
Therefore, it is an object of this invention to provide apparatus for precisely cutting logs and large timbers.
It is still another object of this invention to provide an inexpensive and simple apparatus for precisely cutting logs and large timbers.
To accomplish the above mentioned objects as well as other objects which will become evident from the following drawings and detailed description, the present invention provides apparatus which works in combination with a chain saw for cutting large work pieces or logs at precise angles. The apparatus comprises a support table having guide fences for maintaining a work piece at a selected position. A frame support base having a work surface parallel to the surface of the support table is pivotally mounted to the support table such that the frame support base may be positioned at a selected angle with respect to the guide fences. Support members or vertical rods are secured to the frame support base perpendicularly to the work surface of the support base. Guides or sleeves which are attached to the bar of a chain saw move along these vertical rods. Thus, the chain saw which is securely mounted to the guides can move up and down on the vertical rods as the chain saw blade remains substantially parallel to the work surface. This allows a work piece positioned against the guide fences to be precisely cut at a selected angle.